Search

A three-level buck (TLB) converter has the characteristics of higher voltage conversion efficiency, lower inductor current ripples, output voltage ripples and voltage stresses on switches when compared with the buck converters in continuous conduction mode (CCM). With a TLB converter integrated on a chip, we cannot avoid its discontinuous conduction mode (DCM) operation due to a smaller inductance and load variation. In this paper, we'll present and discuss the analysis, design and control of a TLB converter under DCM operation, implemented in a 65 nm CMOS process. Transistor level simulation results show that when the TLB converter operates at 100 MHz with a 5 nH on-chip inductor, a 10 nF output capacitor and a 10 nF flying capacitor, it can achieve an output conversion range of 0.7–1.2 V from a 2.4 V input supply, with a peak efficiency of 81.5%@120 mW. The output load transient response is 100 mV with 101 ns for undershoot, and 86 mV with 110 ns for overshoot when I OUT = 1 0 –100 mA. The maximum output voltage ripple is less than 19 mV. [ABSTRACT FROM AUTHOR]